The Supercharged Audi 3.0T's Fatal Flaw: Why you need to get rid of your OEM Catalytic Converters

[@brittoningraham6056]

In regard to 0:56 I know exactly why Audi choose to place the converters where they are. Basic engineering says the faster a catalytic converter can heat up the more quickly the car will produce clean air out of the tailpipe. The goal is to get the vehicle into closed loop operating as quickly as possible for emissions reasons as well as for wear reasons because when the car runs in open loop you are wasting fuel and diluting engine oil. Faster warm up times are one of the many factors that contribute to the fact we can now get away with changing our oil at 10k + intervals. Also, a hot converter will clean itself better which is probably why these engines can eat 1qt of oil every 600 miles and still not set off a catalyst efficiency codes which has always shocked me since oil does contaminate converters (it says so on your oil filler cap). Oil consumption is probably a huge part of the failure of the original part.

[@Yvqi72]

That would be the PcV being the original failing part.

[@tedjohnson64]

How would faster warmup make longer oil change intervals possible? I’m missing the logical connection there…?

[@brittoningraham6056]

@tedjohnson64 When running in an open loop, the mixture is rich, and excess fuel dilutes the lubrication abilities of the oil while adding contaminants. Closed loop operation is cleaner and more efficient.

[@amedaius8492]

Also the quattro system puts alot of restrictions on the under-the-car space, and people want to keep their cars lowered the most they can for performance and look. The decision simply makes sense.

[@FloridaBikeSupplyOnline]

I was going to say, if you anything the cat is heating the engine. Not the engine heating the cat. The cat burns @ crazy temps, engine is like 200?

[@fatboyquin]

Knowledge of how to maintain these cars is key and I feel like you’re gonna save so many cars with this series Cam

[@AudiC7Owners]

Much appreciated bro 🙌🏻🙌🏻🙌🏻

[@mab4870]

It was the tune

[@franciscocornejo9753]

@@AudiC7Owners hello how about the 2020 audi a6 3.0t any info on this ones?

[@AudiC7Owners]

That's a C8 with a completely different engine. Not my area of expertise unfortunately

[@DimaHowick-p3z]

@@AudiC7Owners how about 2015 s5

[@WhiteTrashPardy]

Where’s a cat thief when u need em

[@CDLZEL]

😂💯

[@kingdavid3194]

@@WhiteTrashPardy 😅😅😅😅😅

[@prabeeshsidhu]

please never delete these videos!! this knowledge is priceless. Thank you for sharing

[@borisp9499]

This video is wrong. Proximity to cylinder head doesn't kill catalytic converters, it makes them last longer.

[@lolley1100]

Great write up on it! I had worked at an Audi dealer for several years up until 2021. While I had replaced several sets of cats for catalytic inefficiency faults and cracked flange welds, I had never seen them be the cause of any drivability concerns. After 2021, I had went to an Indy euro shop where I still currently work. It wasn’t until I started actually modifying em where I’ve seen em start to have issues. So far, I’ve only seen 3.0 cats be the cause of an engine failure, which was on an APR stage 3 build. For what it’s worth, I live in one of the hottest and humid climates in the states. In my opinion and experience with these, if it’s modded, ditch em. If not, don’t sweat it! 😁😁

[@Vanityvizione]

I have a completely stock 2013 a6 c7 got a little gas smell, may be the cats, may not. You say don’t worry to much?

[@lolley1100]

@@VanityvizioneMore often that not, fuel smell on these is the high pressure fuel pump leaking raw fuel into the crankcase, eventually you’ll get rich faults and hesitation on starting when hot. Pull the oil cap, see if it smells like fuel, replace hpfh.

[@AydenEgbert]

I have a 2014 audi c7 a6 3.0 and I was really wanting a stage 1 tune but it has 110,000 miles on it. Should I not get the tune? And should I be worried about a failure soon, I have to fill a quart of oil every 2 weeks and I cant figure out why?

[@lolley1100]

⁠@@AydenEgbert More than likely piston oil control rings have seen better days. Audi’s spec (since been changed based on hwy/city driving) is 1,000 miles per one quart of oil is “in spec”. But let’s be real, it should be far more lol! Oil control rings either get carboned up or worn to the point of burning that much oil, but I’ve yet to see it lead to a catastrophic failure. I’d PERSONALLY delete the cats for a stage 1 tune, but that’s a tough job as a DIY and expensive labor wise. If you do it as a DIY, reseal the upper timing covers wile ya at it!

[@hundredmajor6661]

⁠@@AydenEgbert congrats.With 2,000 mile difference. Perhaps get new cats before 113,897 miles. Flex pipe is seeping on mine . Dealership warranty replaced an oil pressure switch when vehicle was brought to for raspy sounds and oil smell.

[@dioneyloyola]

This is very true. I had melted pistons all in bank 2 of the engine #6 piston was the worst. My catalytic converter was clogged and it caused my combustion chamber to reach really high temperatures. I did not experience any misfires or rattles until after the damage was done. My data log showed that my cars was running perfectly fine during racing. I learned the hard way

[@AudiC7Owners]

Damn! Sorry to hear that

[@Burr92345]

That’s wild to me! No signs at all?

[@snakkedr]

I'm in the same boat as you are. Spun a rod and had severe knock. Cylinder walls on bank 1 were scored. No misfires prior. My A6 has been stage 2 dual pulley since 2016. I have a slightly lower mileage engine going in with catless test pipes.

[@dioneyloyola]

@@snakkedr mine developed a knock about 5 minutes after I was done racing and in about another 5 it completely siezed. I bought a used engine too but I just gutted the cats. My car is stage 2 double pulley on a e40 tune

[@JoeyS5]

@@dioneyloyola do u know roughly how many miles the car was stock power, stage 1, stage 2 power?

[@Inimbrium]

Dude, this has been happening to my car for years!!! Finally, someone who knows what the problem is!!! Thank you!!!!!!!!! It's a 2012 :)

[@AudiC7Owners]

Get it fixed asap! A scan should tell you if you have catalyst codes as well

[@chriskamen2152]

Catalytic converters need to be hot for the reactions to occur, they are designed to operate at high temp, but a bigger reason they are that close it for emissions, thewy warm up to operating temp faster. If you are melting cats your tune in bad or you had a catastrophically lean running engine.

[@lewisthompson8705]

As a new owner to an A6 exactly like yours, these videos are super helpful. Thank you so much! Definitely subscribing

[@AudiC7Owners]

Thanks man! Enjoy the car!

[@davidallen9246]

This is a great video. Unfortunately, I watched it too late and fell victim to this resulting in catastrophic failure and a blown engine. I bought a 2012 A6 3.0T and went APR Stage 2 with tune and dual pulleys. It was great fun for a few years until it started running rough with misfires. My Indy shop also must not have seen your video and kept replacing coils etc. Then came cylinder 6 catastrophic failure due to exhaust manifold bits going into cylinder I'm guessing. Went the route of putting in a used engine and I pretty much baby the car at this point. Need to show my mechanic this video and address the cat issue before the same thing happens all over again. Thank you for your insight and great video!

[@AudiC7Owners]

That's a painful lesson!

[@mozime2420]

I think this is what I'm going through right now just sent the car in yesterday on a 2012 stg1 , vcdc said piston6 misfire

[@Lizard6376]

2012 A7, OEM Cats, 155k miles, stage 2 DP since 110k. Fearing the day this happens!

[@AudiC7Owners]

I'd swap Em before you have an issue

[@austinmerrival927]

@Lizard6367 Still running ok, no issues with OEM cats yet? 😅

[@Lizard6376]

@@austinmerrival927 Almost 180k and still no issues. Everyday the anxiety worsens lol

[@austinmerrival927]

@@Lizard6376 🤣🤣 I hope I’m as lucky as you once I go IE stage 2 dual pulley (currently at 91k miles) keeping fingers crossed for both of us lol 🤞🏽

[@jasonh.2731]

@@austinmerrival927 any update on the health of your cats?

[@mostlypostie1]

As someone on the other side of the world with a b 8.5 S4, I can confirm everything you said is 100% correct. FYI gutted cats and the 034 X pipe is a pretty good combination to not have the car sound like a straight piped Camry.

[@lauretiu]

i did say this before on one of your videos (i live up north too ND, and we get a lot of salt calcium chloride on the road in the winter) there is an easy way to take them out: take your firewall off (takes about 1 hour if you unplug the engine wire harness from the fuse/relay box) that compartmentalizes your engine bay from the washer fluid and brake fluid reservoir and you have so much space to take them out , you won't believe. i took my cats out 3 times out that way and it took me 2.5h to take both of them off( granted i was lucky and i didn't strip the 3 copper nuts at the top) last time i took them off i upgraded to the cenex exhaust that you had in one of your videos

[@davidsibble7429]

What da…?!! Woow Is that really possible?

[@AudiC7Owners]

One day im going to remove the firewall just to test your theory haha. I know how to remove the firewall from a 4.0TT since that is how you change those downpipes as well. I imagine it can't be that different. When you do it, do you pull the cats out of the top?

[@haditaleb4066]

Interesting.

[@antoniodavino5344]

How do you go about starting to take the firewall off. Looking to do this job soon

[@lauretiu]

@@antoniodavino5344 if you can give me a 1 time use email I can send you some pictures from the time I took out the whole engine with the whole front end of the car

[@mastalee1776]

Sucks to be in cali like me. Soo many unnecessary restrictions

[@cm.5023]

My B6 VR6 Passat had a similar exhaust system but with 4 cats. Thankfully they lasted well over 300k till the trans started slipping. Thanks for your vids, I really enjoy your C7 content.

[@AudiC7Owners]

Thank you!

[@SC-gm3ry]

I've had my S4 for almost 3 years now (2014) and was told by my shop when I bought it that the slight rattle I was hearing on startup was some of the honeycomb that had broken off of my passenger side cat and was rattling inside. So far it seems to be fine, and I haven't thrown any codes as a result, but it has always bothered me and been in the back of my mind that it could give out. I am running an APR stage 1 tune, and have been considering going single or dual pulley, but I would probably also need to do something about the cats at that time as well. What I had been considering were the Magnaflow high-flow cats, but I was viewing that as a 'permanent' solution and wasn't aware that those would inevitably fail as well. I guess I need to look into the local laws about emissions standards and if I can get away with test pipes... thanks for this useful info!

[@jessecooper537]

The rattle noise, might be your flex pipe rattling, due to bad motor mounts. Which is a common problem with the 3.0 tfsi

[@stevenbeatty2643]

I would bet on the timing chain guide.

[@clydestraus5526]

Guys I have a problem on my cgw 3.0L supercharged motor . I have had the epc error once when I hit a dip in the road and started misfire on cylinder 3 been about 2000km I haven't had that error . Is it a problem ? Also I have the rattling startup sound when automatic choke warms up the motor . Also when extremely hot or cold my car motor swings a second or more longer . Sometimes it just cuts off once it's starts like no fuel delivery . Guys I really need help I'm in south africa we have a hot and very humid climate and I bought this car it was going great but now I am encountering these problems.

[@boerieza]

When I went Dual Pulley on the SQ5 I had the cats removed completely. Not only did this sound incredibly bad, but the smell from this engine without cats is truly horrible. I opted to install some Magnaflow small-profile cats into my Milltek downpipes, moving it well away from the main source of heat - and that's solved 90% of the problems. It's still a nightmare to tune the exhaust to sound decent on this engine once you've changed/removed the cats.

[@pxrplexed3501]

I have headers jh motorsport high flow catted downpipes and an awe track, if you went with the touring exhaust it would sound much better imo

[@dennisrobinson8008]

@pxrplexed3501 how much power increase?

[@31marek13]

Hello, very helpful video, i wish i knew this things before. I have A6 C7 with 2.8FSI engine(very similiar to 3.0TFSI but without superchager). Last week when I accelerated uphill, catalyst literally disconect from exhaust manifold. We had to put whole engine from car because there was no place to repair it on car. When we looked on catalyst, it was disconnected from pipe. There wasnt any welds! We had to weld it and other side too for sure. I dont understand why Audi didnt weld it. Decat does not come to mind because of emmision tests every 2 years in our state. I am glad we could repair it and i am glad also that cats were okay because 1cat costs around 2400€. Total price was 1300€ for the repair (because of engine pulling out) but it is still better than buy new ones.

[@AudiC7Owners]

I'm sorry that happened to you!

[@machko1]

Did the exhaust sound raspy with more rattles from the dash area?

[@TheUnhurduv]

Did some research related to gutting the cats and found this potential workaround: The fault code is caused because the exhaust is flowing faster and cooler than the factory downstream O2 sensor is programmed for. Install a spark plug non fouler in the post catalytic converter O2 sensor locations. This will require you to drill the existing hole in the spark plug fouler large enough to accommodate the O2 sensor. Then install the original O2 sensor into the spark plug non fouler. In some cases this will help eliminate the fault code, but this method should only be used for off road applications as it will not meet federal emissions requirements. I saw this in a MT article related to high flow cats throwing codes in the d/s O2. There are also a couple vids for diy.

[@brittoningraham6056]

Oxygen sensors do not sense temperature they sense the amount of oxygen left in the exhaust after combustion. The way fuel is injected creates a wave (very small) of oxygen rich and then oxygen lean air that the front sensors detect that wave then the exhaust gases hit the converters and almost all of the left-over oxygen is used in the chemical conversion process that happens inside the converter creating an extremely flat oxygen lean mixture post converter. This almost waveless signal is highly calibrated, and the aftermarket cats are not matching most likely producing too much of a wave in the signal because they do not convert the exhaust gasses as well.

[@TheUnhurduv]

@@brittoningraham6056 Replace "programmed" with designed in my previous comment. As I understand it, the sensor will not function at all until minimum temperatures are reached (at least 600°F). In which case, a spark plug non fouler would act to retain more heat, while at the same time allowing less exhaust gases to be sampled because of the smaller inlet thereby keeping a fuel rich exhaust from increasing the voltage enough to register as such. This gives a false reading and a voltage that represents an air-fuel ratio close to stoichiometric.

[@brittoningraham6056]

The oxygen sensor heater will take care of the temperature requirement but moving the sensor out of the stream is definitely what makes the wave pattern smaller allowing the car to pass its own emissions inspection.

[@nighthawkviper6791]

For the 2.0T the P0299 Underboost code will have you chasing Doverter Valve, Wastegate Actuator, entire Turbo Kit, Sensors, PCV Valve, etc; a bad Catalytic Converter will throw that code too.

[@HappyPel]

The reason for them being so close to the engine is for emission efficiency. The faster the cats get hot, the faster they work. This is also the reason for a secondary air injector pump and the grumbly / rich start up on VAG cars. They are all added to make the CATs get hot faster.

[@AudiC7Owners]

That makes sense

[@HappyPel]

@@AudiC7Owners That being said... I have a b8.5 s4 with the same engine / cats. They are absolutely nuts for how they have the passenger side one in. It requires SO SO much work to remove / install.

[@miguelnavarro2571]

Another great video, very informative! Question - How's about a recommendation or video on what you recommend should be the first upgrades or maintenance items on the C7. Surely you have a list of things needing to be addressed right off the bat. Cheers to more great content!

[@AudiC7Owners]

That's a great idea! I'll probably do one of those for you guys soon. But in the meantime you can check out our new owners guide video to learn about pretty much all maintenance issues.

[@jonathangipaya]

Such an underrated channel! Appreciate the videos!

[@AudiC7Owners]

Thank you! 🙏🏻

[@MrErikBest]

I have a 2017 Sq5 with 80k dual pulley, just got check engine code -0430, and white smoke from exhaust. Now I have CAP test pipes coming in Friday, going to be attempting to tackle the job. The rasp I'm worried about but I don't really have a choice, currently running stock downpipes and awe catback touring. Good luck with your current engine build!

[@lostnchinatown]

@@MrErikBest how long have you been dual pulley without issues and how was that install? Lol

[@knightriderfan1]

My B8.5 SQ5 is still on stock cats after 100k miles on Stage 2+ tune. I hope they don't fail on me any time soon cause I'd hate to go through the trouble on getting them replaced! I remember when I went to Stage 2+ a lot of people told me to remove the cats since I lived in a high heat climate but I've had no issue with them so far. Thanks for the tip on the aftermarket test pipes with cats! If mine end up failing I'd probably just replace them with OEM ones.

[@AudiC7Owners]

Just keep an eye on them! Some occasionally a car will last a long time on them. Sounds like you are getting lucky!

[@DarkSession6208]

@@AudiC7Owners Hey there, im running a S4 2009, the cats failed on them already but the previous owner put in some new cats, im not sure if they are metal cats. I honestly don't know what to do if they fail on me, the car has a Map, (10.6s 100-200) so im not sure if its a stage 1 or stage 2. But if they fail i honestly think about putting the stock Software on them and buying some used stock cats. Do you think they will last me 50.000km? I would gut them but the problem is the smell and MOT. Keeping the software and installing OEM Cats i guess means they will fail under 15.000km right? I looked into metal cats but people on forums said they also fail the same, so thats also not a option.

[@ezveedub238]

The cats are mounted close to the exhaust because they have to heat up faster to meet stricter emission requirements. Second, they don't fail often, at least not on the dealer repair side with 3.0T. Older 2.7T and 4.2 V8, they failed at higher mileage more than 3.0T. Modified cars, this may be different.

[@AudiC7Owners]

In the modified world it isn't if they will fail, but when lol. And even my friends who is a tech at a dealer told me they deal with failed cats on 3.0t cars all the time on stock cars 🤷🏻‍♂️

[@ezveedub238]

@@AudiC7Owners I don't know about failures in stock cars being an issue. And that's from several dealers I know. They don't even have those cats in stock either checking inventory.

[@davidsibble7429]

Great advise, actually one I’ve thought of often and was more on the side of gutting the cats on my stick system. Good thing is that my car sits at home in the days and I drive a work van, so it’s out sporadically on weekends more than anything else, ( only mods are APR 1 & K&N)

[@AudiC7Owners]

Thanks!

[@Moments-in-Frames]

Great video, I'm glad i found your channel! I just upgraded from my 2009 a4 to a 2014 a6 3.0T, i love it and I'm trying to take care of it for as long as possible but I'm still learning a lot about the car. At 9:08 you mention the 3 ways you can mitigate the failure of the catalytic converter. My question is, which of the 3 ways is the best and also which is the most cost effective to have done at a local shop? Do you also know the average price I would spend on each? I also looked into the test pipes on can auto and it says that they increase performance but earlier in this video you mentioned that increased performance can quickly wear on the catalytic converters, does that apply with this as well? Thanks in advance, love your videos!

[@AudiC7Owners]

Test pipes = No Cats anymore. It's just a piece of pipe. You will have to call around to find a shop to install them. Will probably be about 6 hours worth of work.

[@Moments-in-Frames]

@@AudiC7Owners thank you! I also notice on the website they have options for a heat shield or black ceramic coating on the pipes. Do you think either of those options are worth it?

[@AudiC7Owners]

I would do the heat shield if it were me

[@Moments-in-Frames]

@@AudiC7Owners thanks a ton!

[@Looey-lu]

​@@AudiC7Owners if we take this route are we looking to change the sound of the exhaust? I don't want to change any sound to be honest

[@Infantryman662]

Great video! I've heard some people say if you go stage 1 you don't need to do anything to your catalytic converters and like what you're saying if you just boot it a lot (send it) you're at risk. I bought my S4 because of how much fun it is to send it so I'm always booting it. I appreciate you explaining everything in great detail. I am not in an area where I need to pass emissions, but I don't want my exhaust to be louder either. But higher on my list is cost I don't want to spend good money on something that'll fail again down the road. Sounds like I'm going gutted cats, the wife is going to love it haha.

[@AudiC7Owners]

You could buy CAP test pipes & then sell your oem cats to recoup the costs or pay for the labor to remove them.

[@Alcalfa]

It is quite normal to have cats right at the exhaust manifold, my '04 Toyota has them there and the '01 Golf also. Really nothing to be surprised about... This isn't the late 80s any more with them a few feet from the exhaust ports.

[@hyperspaceexplorer5594]

Watching this video makes me close to trading in my 2013 Q5. Currently, there are multiple fault codes-stuck flap open, misfire on cylinder 3, chugging coolant, using too much engine oil

[@AudiC7Owners]

Sounds like you have leaking intercooler cores along with a bad pcv. I definitely would not drive it until you get all of that sorted.

[@Tyler_Flynn28]

I have my B8.5 S5 I’m at 45k miles rn. I do have perfect maintenance’s and I don’t race my car or beat on it. It’s also stock but I three are the maintenances in looking at getting done soon for sure! Great video! Btw I’m also pretty sure Audi put the cats near the engine to help warm it up faster and it helps the EPA emissions as silly as that is!

[@JustPlainRob]

It's surprisingly a lot easier to swap these downcats on the SQ5. It's like the S4... but with more room for activities. Much less headroom on the hobby garage lifts though.

[@AudiC7Owners]

That's a huge fact. SQ5's are WAY easier I thought the C7 would be similar, but they aren't lol

[@DeanAndryeyev]

Thanks for this video. Although I'm looking at a B8.5 it was very helpful regarding the motor.

[@videodlrvm2]

Had a water pump prop (plastic made) OEM... split and kill my Q7,, had only two spades and worked fine at the shop but as soon I hit the road the temp went up... It took a blown head gasket to tear down and discover the fatal flaw.. get the metal prop from aftermarket ... It also killed tons of Pointers and other VW's...

[@campbellsoup4910]

Very good information on Cat's. My question is, when you start upgrading power with tuning and pulley's is it a good practice to gut cat's or upgrade exhaust system first? Also, is there a diy way to check condition of Cat's? 2012 A6 prestige sports 3.0t 80k

[@AudiC7Owners]

It's always better to deal with your cats first. An aftermarket exhaust has no performance benefits. Just makes you smile bc of loud noises haha.

[@campbellsoup4910]

@@AudiC7Owners Copy that! Thanks 👍🏾

[@hondarr9208]

I have 2011 S5 and had this issue. Passengers side cat was busted.. Audi charged me +4000€ to replace a new one.. only the cat cost over 2000€. Not a cheap car to repair. I hope that drivers side cat won't fail on me soon too :D Thanks for great video! I hope I watched this earlier.

[@homeaudiobasics]

I know this is an old video but to answer your question about why the cats are so close to the heads its because that maximizes the heat into the cats getting the catalyst as hot as possible as fast as possible

[@cwmedia_cn]

I wanted to do test pipe for so long but the fact it’s a pain in the butt job scared me away. Then the cat on bank 1 on my SQ5 finally went. Luckily the weld failed and broke off the flange before it did a lot more damage to the engine.

[@forgottenknowledge8917]

At 300,000km my cat has done its job. I gutted it two weeks ago and have kept the resonator off. The muffler came of ages ago. All you need is a 45⁰ bend pipe, a metre of straight pipe to have the tip come out before the rear wheel, and some clamps. Band clamps are easy for joining pipes. My little van sounds like an old truck with the loud turbo whistle, haha

[@ar00780]

Good video. 👍🏻, I did dual pulley, intake, tune. Lost all compression cylinder one. Wasn't until I yanked the cat, noticed oil pooling out of manifold. Inside of cat cracked. Took head off, broken ring on cyl 1. Wish I saw this video before the mods .

[@AudiC7Owners]

Sorry to hear that man. Tough luck

[@bangurowned]

Sorry to hear man. How many miles were you at? What’s your plan now? Rebuild or swap?

[@ar00780]

@@bangurowned Ya it sucked. It has 137, 000km (in Canada) so 87,000miles. So a baby for my S4. Found a used motor, on a stand now. Replacing pcv, timing chain, carbon clean out, thermostat and any thing ibwont have to worry about. Race pipe and down stream cats. Oh and a clutch too😁

[@bangurowned]

@@ar00780 I’m about to buy a 2016 a6 with 59k miles. So I’m super nervous about this popular problem with them. Would you still buy it again?

[@ar00780]

@@bangurowned I am going to give this 3.0 another chance. This is suppose to be a strong motor. As a mechanic, it makes to much sense that the location of these converters is ridiculous. Watching this video made even more sense. Down stream hi flows. Hope will fix this. In Ontario we still have emissions laws; hence the converters

[@craigauty6756]

Mine are drilled out cats. And done a muffler delete. Sounds better than a friends with a stainless steel full exhaust system. Heard mild steel sounds better than stainless also

[@alejandrohinojosa7407]

So does this also happen to 23 Q7 models with the 3.0 engine?

[@cjbht19minaret]

From 90k miles to 130k miles I’ve had failed cats, 2x failed PCV, Failed fuel injectors, failed coil packs, failed timing chain, failed crank pulley, 2x failed flex pipes on the down pipes, and carbon build up on the valves. This 2013 A7 has cost me almost 2x the price to maintain and upgrade it than the price I paid for it in about a year. That being said, I am running an APR ultracharger, JHM stage 2+ ultra ecu and tcu tune, JHM test pipes, JHM 207mm OAD crank pulley, JHM heat exchanger, K&N performance air filter, O2 spacers, JHM HFC and baffled downpipes, and an awe touring exhaust now and the car is currently in the shop for a new PCV and timing chain service. I’m hoping the leak down test brings good news after they complete the service mentioned above. From what I’ve heard, I can pass smog being on this tune as long as the O2 spacers do their job and I can pass visual inspection.

[@AudiC7Owners]

It pays to learn how to do most of the work yourself haha.

[@cjbht19minaret]

@@AudiC7Owners That’s very true!

[@daniellim3175]

@@cjbht19minaret I'm also running the JHM test pipes, HFC and baffled downpipes with 02 spacers. I'm the JHM stage 2+ ultra ecu and tcu tune as well. I'm hoping JHM comes out with the E40 tune before summer hits or I might switch to 034 to get their E40 tune.

[@luisencarnacion251]

@@daniellim3175 What O2 spacers are you running?

[@MindOverEverything]

Christian, was your failed pulley the stock one or an aftermarket? Also did your cats fail after you were at stage 2+?

[@Machtig-1]

great info. thinking about moding my A7 and hadn't thought about the cat. great heads up. thank you so much for the vid.

[@AudiC7Owners]

No problem. Good luck!

[@Da86suvivr]

Incredible video. I was able to get in on the test pipe GB thanks. Im in NY and plan on getting generic cats and install them on my non-reson downpipes to hopefully pass NY OBD emissions and kill the rasp. Hopefully with test pipes and generic cats along with the MF x-pipe and resonator I can accomplish both my goals.

[@jasonh.2731]

Were you able to pass NY emissions and kill rasp with the setup?

[@jonathanlin4009]

I have an Audi a6 c8 getting a catless dp intercooler Apr intake and a weistec engineering etc and tcu tune next Tuesday so excited

[@brooklynnets2482]

I have multiple questions regarding my 2014 C7 3.0T (126k miles stock) that just came down with an exhaust issue coming from the passenger side, suspecting it possibly needing a flex pipe replacement or something with the resonators. Been driving it for about 75 miles after the issue started happening. Will be bringing it to a local shop to get estimates and second opinions. No check engine light or any indication lights came on as of this writing since driving it 75 plus miles after I noticed the issue (rough idle, and loud unpleasant exhaust noise and vibration while accelerating). Based on this, should I worry about the cats failing at some point if I chose to replace/weld the flex pipes at a muffler shop? And is this the best route to go, or should I just replace the exhaust pipe on the one side, which I am aware will be expensive? Need some opinions...

[@ronkirkham3410]

Luckily I don't have emissions to worry about and I did would you did on one of my vehicles cut the cats out gutted them and had them welded back in and everything was great. I'm thinking like you said that's the way to go besides removing some resonators and changing the factory mufflers but I don't really want a ton of drone in the car so any input is greatly appreciated

[@mephistohate]

Australian 2012 A6 C7 3.0T running IE stage 2 dual pulley, had my exhaust shop install some high flow cats, he was able to remove the stock cats out through the suspension area and installed the high flow cats further along the exhaust, have some O2 sensor extensions and O2 sensor spacers, still gives an engine light now and then but i can live with that

[@AudiC7Owners]

Nice!

[@planetfade2522]

Very informative video! My car has a vibration at idle but gone with I get to speed.. another thing I wanted to note is that when I start to slown down and at around 2-1200rmps it get worse could it be the cats being clogged ? Thanks and keep up the good worrk!

[@AudiC7Owners]

That's likely not from cats clogging. That could be from engine mounts or control arms wearing out. Do you have any suspension modifications?

[@jordonwhitney1911]

That is the most effective location to have the cats -- that's why they are there. The closer to the exhaust ports of the engine the better. You will not find a primary cat on any vehicle located at any significant distance from the exhaust manifold.

[@tomnichol8146]

I have a 2012 w/APR Stage 1 with about 76k on it. I don’t beat it but I don’t baby it. If I gut the cats won’t the lack of back pressure cause a problem? Are there O2 sensors I need to retain? If I eliminate O2 sensors won’t it effect the performance of the car? How exactly does one gut a cat? I have no emissions inspections where I live. I was considering the Magnaflow system, would that be annoying with the gutted cats and therefore I should stick with the stock exhaust? I plan to try and head this off before it happens, hence all questions. Thanks for an outstanding video!

[@AudiC7Owners]

1) it won't effect the backpressure enough to effect performance 2)your 02 sensors stay in place, but you will get a CEL. It won't effect performance negatively. 3) remove your cats, then use something to remove the inside material. 4) annoying is subjective to the person. There will be rasp if you don't make sure the aftermarket exhaust is properly resonated.

[@tomnichol8146]

Awesome thank you so much for the quick response

[@Nordic_Mechanic]

The catalystic converters are there because the EPA required audi to make them heat faster. Cant have 30 second of pollution. It's also why in the mid 2000s the 4.2 v8 was canceled from the a6 chassis. The change to closer catalytic converter worked for the new a8 design but there was no room for them in the older a6 platform

[@Divine_Serpent_Geh]

Yeah it all comes down to pressure from bullshit emissions.

[@hsk021]

Replaced both bank 1 and bank 2 in the last year. $3k each from dealership.

[@mtnbikerva1]

93,400 miles stock 2014 Audi Q5 3.0t mostly highway mile, any of this apply to my vehicle? Preventative service beyond manufacture recommendation? If I go stage 1 does it change maintenance and repairs? Thank you!

[@user-vo5my2dt2u]

I have a slight rattle at certain RPMs and wonder if it might be leaking some exhaust gases pre/post converter. No codes, misfires etc. Does this seem accurate? Great content as always!!!

[@AudiC7Owners]

That is probably from bad flex pipes, but it would be impossible to tell without an in person inspection

[@user-vo5my2dt2u]

@@AudiC7Owners good point, thank you. I’ll get it to a muffler shop to inspect further.

[@braydensegerman926]

I am thinking of buying a 2017 a6 3.0 with 44,000 miles. I’m pretty sure it’s completely completely stock. Should this be a worry for me I only plan on putting an exhaust on the car

[@Wopdela.B]

Thank you I been dreaming of having a 3.0 tfsi engine

[@Ben-wf8rl]

I was just at 136k miles with 50k being on an 034 stage 1 tune so I was expecting to lose cats soon but I had scoped O2 sensor, logged O2 sensor readings, and done cat checks with VCDS regularly however just a couple hours after I did my last cat check with vcds when I was driving on the highway I did a light pull and immediately something felt wrong with slow acceleration and then epc due to repeated misfires. I pulled off the highway as soon as I could but it was about a mile after the epc turned on and when I tried to restart my engine it struggled to start and was even worse. I realized my cats had clogged and I figured most of the damage had already been done so I flashed the 034 test pipe tune and 2 stepped my cats out a little, that fixed the epc so I went and did some highway driving to heat up the cats and then 2 stepped the rest of the cat material out, it seemed to work very well with no back-pressure or misfires after but im going to go do a compression test and clear out cats by dropping the downpipes later today. Are there any other tests I should do to make sure I didn’t damage my engine? Also do you know if I still need to get my cats out to get them reinforced?

[@AudiC7Owners]

Just keep a close eye on its performance And yes, the cats have to be removed to be reinforced

[@LPKizzle]

Commenting on adding a downstream CAT, wouldn't you just get a CEL from the O2 sensor or if you add it downstream you would also need to add the spacers?

[@murraydmark]

Does driving with a Check Engine Light from having test pipes hurt anything? Perhaps messing with Air/Fuel mixture? Which would you recommend as far as safety? Not trying to switch tuners right now, and my tuner does not have a test pipe file. Bonus question: the SAI system. If I have test pipes, are the SAI ports less likely to clog? And if they do, would it even matter in my case?

[@AudiC7Owners]

No. A test pipe cel won't hurt anything. Reference the SAI, I'm not sure what makes them clog faster. Not a lot of info out there about it for our engines.

[@riyazes]

Great video! Very well explained

[@AudiC7Owners]

Thank you!

[@FordPickUPRed]

Miss my S4 even though it left me stranded twice on the hwy.

[@AudiC7Owners]

What were the issues?

[@ronkirkham3410]

Great video man I'm new or new words Audi but not new to automotive in general I've had lots of vehicles 600-horsepower mustangs and GMC big block trucks etcetera but I'm getting a 30 ts5 and I definitely have some questions about the exhaust and would be great if we get touch base even for a couple minutes

[@ronkirkham3410]

All your videos are 100%.. thanks again

[@Matt-68V]

If im in a country that is strict on emissions, is there anything other than replace with OEM part? Gutting, test pipes, long tubes will all fail emission standards correct? Do you know any aftermarket that just sells better quality cats?

[@09kmacks]

So, I bought a '13 S4 a few months ago, had no issues during the summer, but as soon as it got cold I had a PCV warning about insufficient airflow, solved that by relocating the hose coming from it up by the passenger side quarter panel. and removing that cover over the intake for increased airflow. Since then, no PCV warnings, but I replaced the water pump and had a transmission service done, and now, whenever it's foggy out, or raining, I get a transmission error code/warning that says not to use reverse, and then the TPMS light comes on for a second and then they both go away, but TPMS will keep popping up every other minute until I turn off and restart the car.... please help

[@billybadass7722]

Lol yeah the diy on the cats is rough but it's do able, I took about a week with on and off work to get my headers installed without completely removing the engine, tip for anyone watching, the manifold and cat come out substantially easier than the headers go in

[@billybadass7722]

I haven't heard the test pipes or gutted cats yet but I know that the headers are not to raspy but right at 1.5k to 2.5k rpm it's not great, but im only running the center res currently

[@thevictim2072]

There is a great side benefit to having the cats up in the engine. They will never be stolen.

[@AudiC7Owners]

Lol I think most enthusiasts would be glad to have theirs stolen

[@riteshnowbut1898]

Hi Sir very informative video... Tell me someting.. I have a 2011 A6 2.0tfsi... Should i gut out my cat before it clogs? Or do I have to tune the ECU inorder to do so? Also would the car have any performance problems by gutting out the cat converter...?

[@AudiC7Owners]

Your car doesn't have any issues with cat failure so you don't need to mess with it unless you want to for sound purposes.

[@janbochnig3198]

Good Evening, I have a 2017 a7 c7.5 competition stage 2 ( intake, x-pipes ) . So I may get the same issues one day ? I’m planning to get AWE touring Edition exhaust with resonated downpipes. Thank you !

[@ramboandspecialk8469]

Would taking the secondary firewall out give you enough room to pull them out of the top like they do on a s6? My cats just went bad and I’m trying to figure out the easiest way to do it.

[@Rugged_again]

Another great video my guy 👌🏾👌🏾 and I'm glad to hear that the worst part of this motor is just the cats!!!🙏🏾🙏🏾

[@AudiC7Owners]

There are other issues that could happen... It's just with the cats they almost assuredly WILL happen.

[@mariocicciarello2154]

Excellent video and info as usual Cam! Question, do additives like Cataclean every quarter help at all?

[@AudiC7Owners]

Marginally at best

[@mariocicciarello2154]

@@AudiC7Owners I appreciate the quick reply Cam! Have a great week and glad I found you and your expertise!

[@AudiC7Owners]

@@mariocicciarello2154 No problem man! Thank you!

[@jacobstarling4927]

Just hit 67k miles on my stock s5. In California so emissions are a pain, if I don’t plan on going w/ performance mods and don’t abuse it could I see the cats lasting a while longer? great video as always 👍🏼

[@AudiC7Owners]

If your car stays on stock tuning and you don't beat on it very much then your OEM catalytic converters should last a very long time

[@gst3601]

Hey, thanks for the info. So i had a stage 2+ tune done on my 13 A8, crank and turbo pulleys. And ever since my chech engine would come on periodically.. not too often, but the code says " catalyst system efficiency below threshold bank 1"... can you let me know if my cat needs to be replaced or o2 sensor??? Please help

[@bsheers2003]

great video... deters me from any idea of making a C7 my next DIY car. still driving an older C5 2.7t allroad, with just 175k miles. if you have any experience with this engine, would love to hear your comments and warnings.... thx

[@AudiC7Owners]

Don't let this deter you... Test pipes on 3.0t's area like turbos on 2.7t's. At least the engine doesn't have to come out to replace the test pipes

[@bsheers2003]

@@AudiC7Owners wondering if you 've seen this video about the 3.0, and what your comments would be: [ kzbin.info/www/bejne/pH_bqmavgalleZI ]

[@MindOverEverything]

My S4 has 72k miles and has been Stage 1 for about 3k, so I'll need to take care of this sooner than later. I saw a comment down below about removing the firewall(?) to get easier access. Do you know anyone who has done that? Maybe a video or thread somewhere?

[@dylandalka8700]

Mine did the same thing you were saying about a month ago changed the plugs and coils and it has been fine but now after hearing it makes sense. I only had a misfire in cylinder 1 and 3. However I’m in the military and idk where I could get stationed so I’m scared of failing emissions tests. What would you recommend?

[@AudiC7Owners]

Doesn't your car stay registered in your "home state" while you are in the military?

[@FUNNYVlDS]

How loud are the test pipes to replace cats, will it be extremely loud I live in a hoa and California I don’t really wanna worry about getting state reffed or the cops called right away

[@lazaroastudillo6787]

Just changed all spark plugs and cylinder 3 starts misfiring swapped coil packs but still missing cylinder 3 I was going to replace the fuel injector but I really hope it’s not the cat

[@AudiC7Owners]

Could be a leaking intercooler core as well

[@SidlineRunners]

awesome info. Having issues though… had a bad coolant leak that did hydrolock. So new pcv thermostat water pump valve cover gasket intake manifold gasket… Major cleaning and oil flushes. Vehicle runs fine but now i have misfire on 3 and 6. you have two videos that are taking me to different ways. is it the super harder intercooler leak? or is it the clogged cats? I did have cat codes during all this rehab. I really am at a loss at what to do. it’s a 2014 a7 with 91k bought at auction this way. any advice would help! thanks in advance

[@AudiC7Owners]

You can pull the supercharger to look for signs of intercooler core leaks. But if you have cat codes then you need to drive easy until you resolve that

[@martinnikolaev3555]

How did you manage to deal with the O2 sensors after gutting the cats? Is it possible to tweak the ECU, so that it acts as if everything is fine without popping any CELs?

[@SapphireSweed]

Any issues with the B9 3.0T cars? We have a B9 (2019) S5 cab, and also looking in to a B8.5 SQ5 so this vid popped up. Thanks

[@AudiC7Owners]

Related to their cats? I haven't heard of any issues

[@nick-qv2iz]

Hey, love your videos! You have a great channel! Question, I have a 2012 Q7 with the 3.0t and I’d like to stage one jackal tune it and maybe stage two down the road…on the q7 as well do you recommend gutted cats? And do you have any heat exchanger recommendations for the q7?

[@AudiC7Owners]

Always mercracing for heat exchangers. And cats are always a concern. I'd have money set aside to deal with them when the time comes.

[@yoshi10152010]

I live in Cali where can I go to replace my cats and relocate them?

[@AudiC7Owners]

Best bet is probably another state.

[@reelrocknrolla4251]

Does this apply to the newer q7s as well? I think they updated it in 2017

[@ianirving8494]

I have a ‘16 C7.5 with around 65k miles. Totally stock, driven hard on occasion for short periods of time, but pretty casual most of the time. Haven’t noticed any oil consumption issues or misfires. Should I be concerned about this yet?

[@AudiC7Owners]

Generally, stock cars that aren't driven hard shouldn't need to worry about this... But it's something to be aware of

[@audikingzz_4053]

I unfortunately had the same problem, which converter do you recommend can you give a link. thanks in advance

[@garys7410]

I have a 2016 c7.5 stock daily driven no tracking or anything, what about the oil i recently took your advice changed oil with motul 0w40 x max 100% synthetic. Its a full SAPS oil people say it can degrade and clog the cats quicker...whats your take on it? Im a fan from 🇨🇦

[@AudiC7Owners]

The only way oil will clog the cats is if your car is burning it excessively like when your pcv fails. As long as you monitor your oil consumption and stay on top of it then you should be good for a long time.

[@garys7410]

@@AudiC7Owners good to know, hit 65000kms no burning or top ups in between oil changes 🤞

[@OkeliOY]

Great video. Great explaining things.

[@user-Alhassany]

Thanks for the awesome content If you would please get rid of the music in the background it was distracting

[@AudiC7Owners]

Most people like it, including myself. Sorry it bothers you, but hopefully you can look past it in future videos.

[@jydolicious2502]

Great video, but I have a question about my 2013 Audi A6 C7 3.0t. Everytime I start the car first time in the morning I get a faint smell of engine oil. Is this normal?, because it only happens in the morning and there is no oil leaks anywhere in the engine. My guess was perhaps there is a valve that vents the pressure in the engine every morning. Any ideas?.

[@AudiC7Owners]

Nope. If you smell oil is because it is leaking or burning off somewhere

[@lonniesanchez2732]

Leaky valve cover gasket probably.

[@danthemansrepreviews5644]

They dont make a cat that you can just put in down the exhaust more? Like gut the oems and put back, or just put in a downpipe where they were?

[@danthemansrepreviews5644]

Nevermind you just said to do this

[@carlsenx2175]

Great video! Got some misfire on cylinder 1 and 3 couple days ago. Already scheduled a service for carbon cleaning and new fuel injectors but still worrying about cats. Do you have any suggestion for getting a high flow cat? What brand would you recommend or what product? Thank you so much!

[@AudiC7Owners]

Gesi's are the nice ones you can get. Just put them downstream & not in the oem location

[@carlsenx2175]

@@AudiC7Owners Much appreciate you

[@S60Rguy]

Not sure if you monitor older videos but I wanted to ask what you suggest for my situation (thinking maybe more options available now). 2012 A6 3.0T with dual pulley APR tune. 128k miles and stock cats/exhaust. I've been using my P3 guage to reset the P0420 code for awhile now. At this point the code comes back on the same day I reset it. I also know its probably only a matter of time before P0430 shows up next. Are there any new options for high flow cats since you made this video? I started looking at JHM but i want to keep the car either quiet or tastefully sporty sounding. I also have to be able to pass emissions.

[@AudiC7Owners]

If you are dead set on putting cats in the oem location check out Garage Auto Sports. People are having good luck with them. Otherwise, get test pipes from Canadian Auto Performance and install cats down steam. CAP has catted mid pipes too

[@S60Rguy]

@@AudiC7Owners Thank you!

[@dtrapalot7018]

So what if you replace the cats with test pipes what do you do about the check engine light that’s gonna come after that?

[@AudiC7Owners]

That depends on how little or how much you want to defy the EPA lol.

[@dittottid]

Hi sorry I did not understand when you said "gut your cats, put them back in" what did you mean by this? Thanks!

[@likasomebodiefakku]

Turns out I have an exhaust leak near the cats, if you touch the cat it literally moves, I suspect its the flange, I cant get to a shop until Tuesday, Im curious if this is something that can be fixed with the exhaust in the car or will it have to be removed, Im almost certain its the flange in between the cat and the exhaust manifold

[@AudiC7Owners]

You will just have to unbolt the mid pipes from the cats. Getting the cats off the headers and out of the car is a nightmare though